Strong opposition to the death penalty in Massachusetts could play a critical role in the trial of Dzhokhar Tsarnaev as lawyers for the alleged Boston Marathon bomber consider whether to seek to relocate the trial outside of Boston, legal observers said Friday.

With seemingly strong evidence against Tsarnaev, his defense lawyers may see the state’s opposition to the death penalty as an advantage if their end-game strategy is to simply save his life in the event of a conviction, the observers said.

“Where else in the country is there such a strong, anti-death-penalty sentiment than in Boston?” said Daniel S. Medwed, a professor at Northeastern University School of Law.

The strategic considerations for the high-profile case took on new weight Thursday when the Department of Justice announced it would seek the federal death penalty against Tsarnaev in the April 15 bombings that killed three people and injured more than 260.

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If Tsarnaev is convicted, a federal jury would then consider whether to sentence him to death. Massachusetts courts banned capital punishment in 1984, but Tsarnaev could still be sentenced to death because he faces the charges in a federal court. But an execution would have to be carried out in a state that allows the death penalty.

Allison Burroughs, a former federal prosecutor who has helped prepare a death sentence case in the past, said the backdrop that the crime occurred in an anti-death-penalty state makes it more likely that the defense would not try to move the trial to a new venue. She also raised the prospect of a plea deal that could result in a life sentence.

“It’s not like you’re going to be able to transfer the case to a state that hasn’t heard about the crime. Everyone has heard about the crime,’’ said Burroughs, a lawyer with the Boston firm of Nutter McClennen & Fish. “Massachusetts would be a pretty friendly state, with no death penalty.”

But Nancy Gertner, a retired US District Court judge, said
the issue could be complicated. She pointed out that it could be difficult to pick a jury of people from Eastern Massachusetts who have no ties to someone killed or injured in the Marathon bombings.

“This is a case in which the government will argue that the victim was Boston,” she said. “Not an individual, not someone in particular, but the city.

“It’s an open question, and a complicated balance,” Gertner said, noting a Globe poll in September that showed that 57 percent of Massachusetts respondents supported a life sentence for Tsarnaev, compared with 33 percent who favored the death penalty.

US Attorney General Eric Holder Jr. on Thursday authorized prosecutors to seek the death penalty for 17 of the 30 charges that Tsarnaev faces in the three deaths and numerous injuries caused by the bombings. Tsarnaev is also accused of killing MIT police officer Sean Collier.

His older brother and accused accomplice, Tamerlan Tsarnaev, 26, died in Watertown in a confrontation with police when the brothers tried to flee the area.

Holder’s decision sent ripples throughout the country and world and stirred mixed emotions among bombing victims and their families, politicians, and law enforcement officers.

On Friday, Tsarnaev’s great-uncle said from Russia that the family does not trust the investigation and the case against him.

“There is no real evidence against Dzhokhar,” Dzhamal Tsarnaev said in a telephone interview conducted in Russian. “The whole world knows that he is innocent.”

He said, “Dzhokhar’s parents are shocked and are in complete disbelief,” and that his mother, Zubeidat, “can’t even talk about this. She is in complete shock.”

Heda Saratova, a human rights activist based in Chechnya who is close to the family, said that Zubeidat and her husband, Anzor Tsarnaev, have been advised by their lawyers not to comment to the press.

Gilberto Tercetti Jr., the owner of Junior Auto Body in Somerville who knew Tsarnaev and his family, said he supported the death penalty in this case, but also said he would not mind a life sentence, saying “death is too easy,” and that in prison “at least you know he’s suffering.”

Richard Donohue, an MBTA police officer who was seriously wounded by a gunshot during the Watertown confrontation, issued a statement after the death penalty announcement, saying it “reflects an important step in the judicial process.”

“As we await the trial, I hope all those affected by the events surrounding the Boston Marathon bombings continue to heal both physically and emotionally,” he said.

Tsarnaev’s lawyers have not commented.

Holder has said in past speeches that he personally opposes the death penalty, but legal analysts said the decision to authorize capital punishment for Tsarnaev was expected, considering the nature of the domestic terror attack.

“They went after the Boston Marathon, an iconic event, there were a lot of injuries, deaths, including the death of a child,” said Burroughs. “It had real terrorist overtones, and I think there was a lot of political pressure to seek the death penalty. If not this case, then what case?”

But Burroughs, noting the time and significant costs of a death penalty trial, added that Tsarnaev’s lawyers could still try to negotiate a plea agreement and persuade the Department of Justice to agree to a life sentence, noting the state’s opposition to the death penalty.

“I think it would have taken a lot of political courage to walk away from the death penalty in this case,” she said, “but I certainly think a life sentence is still possible.”

US Attorney Carmen M. Ortiz has said she supported Holder’s decision and would move forward with the prosecution. She and defense lawyers were able to make recommendations to Holder.

Since 1988, when the federal death penalty was reauthorized for certain drug cases and later for a host of other crimes, the Department of Justice has sought capital punishment for 492 defendants, although only three were executed. The rest either died while awaiting their appeals, are appealing, or the death penalty was dropped for a range of reasons.

The United States has sought the death penalty in Massachusetts cases three other times since 1988. In the case of two Dorchester gang members a decade ago, the prosecutors ultimately dropped the charges and the men were tried in state court.

For Kirsten Gilbert, a former nurse who was convicted in 2001 of administering lethal injections to patients, a jury chose a life sentence rather than the death penalty.

A federal jury in Massachusetts agreed to issue the death sentence for Gary Lee Sampson, an admitted serial killer, in 2003, though the decision was vacated after a judge found that one of the jurors withheld information. Prosecutors are seeking capital punishment in a new trial.